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Xylella fastidiosa

First reports of Xylella fastidiosa in the EPPO region

- Special Alert -

 

Why: As Xylella fastidiosa represents a very serious threat for the EPPO region, the EPPO Secretariat intends to provide on this page a brief description of the pathogen, as well as an easy access to specific EPPO data and other useful resources.
In the EPPO region, X. fastidiosa was first recorded in 2013 in Puglia, Italy, where it is causing serious damage to olive groves. In Puglia, the subspecies which has been detected is X. fastidiosa subsp. pauca. In addition to olive trees, the bacterium has been detected in numerous other host plants (mainly ornamentals).
In October 2015, the bacterium (X. fastidiosa subsp. multiplex) was discovered in France on the island of Corsica on Polygala myrtifolia plants (ornamentals). It was then found on the mainland, first in the municipalities of Nice and Mandelieu-la-Napoule (Alpes-Maritimes), and then other foci were found in Alpes-Maritimes and Var departments. In France, most infected plants were P. myrtifolia and the subspecies which occurs is X. fastidiosa subsp. multiplex (thus differing from the one found in Italy).
In all infected areas in Italy and France, eradication measures are being taken.
 

NEWS

September 2016: publication of three
EPPO Standards on Xylella fastidiosa
Diagnostic Protocol
Inspection of consignments
Inspection of places of production

13th of October 2015: the French Ministry of Agriculture confirmed the detection of Xylella fastidiosa on the mainland, in the municipality of Nice (Alpes-Maritimes) in one Polygala myrtifolia plant. Press Release (in French)

22nd of July 2015: France reported the first detection of Xylella fastidiosa in Corsica. The bacterium was detected in a commercial area in Propriano on ornamental plants (Polygala myrtifolia).
FREDON-Corse (in French)

     
In order to prevent entry and spread of X. fastidiosa within the European Union territory, specific EU phytosanitary measures were published in May 2015 (with some admendments in December 2015).
     
     
Symptoms on olive
Symptoms on olive

Symptoms in Puglia on olive trees. All pictures of symptoms on olive trees were kindly provided by Donato Boscia, Istituto di Virologia Vegetale del CNR, UOS, Bari (IT), Franco Nigro, Dipartimento di Scienze del Suolo, della Pianta e degli Alimenti, Università degli Studi di Bari (IT), Antonio Guario, Plant Protection Service, Regione Puglia (IT)

Situation in Italy: In mid-October 2013, the NPPO of Italy informed the EPPO Secretariat of the first detection of Xylella fastidiosa (bacterium included on the EPPO A1 List since 1981) on its territory. In Southern Italy (near Lecce, Salento  peninsula, Puglia region), quick decline symptoms were observed on olive trees (Olea europea). Investigations showed that symptomatic olive trees were generally affected by a complex of pests: X. fastidiosa, several fungal species belonging to the genus Phaeoacremonium and Phaemoniella, and Zeuzera pyrina (leopard moth). In Italy the disease has been called 'complesso del disseccamento rapido dell'olivo'. Although an unconfirmed record of X. fastidiosa in Kosovo was published in 1996, the presence of this bacterium had never previously been confirmed in Europe. Following the reporting of an extensive leaf scorch and dieback of olive trees, spreading rapidly in the area of Salento (Puglia region), the Regional Plant Protection Service promptly initiated investigations to identify the possible causal agent. These surveys were carried out in collaboration with experts from the University of Bari and the Consiglio Nazionale delle Ricerche (CNR). The systematic screening of samples taken from symptomatic olive trees (many of them were a century-old), revealed the presence of extensive brown discoloration of the vascular system. Portions of xylem tissue taken from symptomatic olive trees were subjected to mycological analysis by isolation on different growing media. Fungal colonies were obtained and identified by morphological and molecular tests. The results showed the constant presence of fungal species belonging to the genus Phaeoacremonium, the most frequently found species was P. parasiticum followed by P. rubrigenum, P. aleophilum and P. alvesii. Species of the genus Phaeomoniella were also isolated. According to the NPPO, this is the first time that P. parasiticum and P. alvesii have been detected on O. europaea in Italy.
In addition, these samples from olive trees were subjected to molecular analysis using specific primers for X. fastidiosa which gave positive results. The analysis was extended to almond (Prunus dulcis) and oleander (Nerium oleander) plants which were growing in the vicinity of affected olive trees and showing symptoms of leaf scorch. The results were also positive. Further serological tests (DAS-ELISA with 2 commercial kits) confirmed the presence of X. fastidiosa. The NPPO stressed that the definitive identification of the bacterium still awaits its isolation in pure culture in order to perform pathogenicity tests. In addition, further investigations are on-going to identify the bacterial strain, to evaluate its pathogenicity and identify the putative local insect vector(s). It is recalled that X. fastidiosa has an extensive natural host range (more than 200 species), including olive from which the bacterial genotype A (pathogenic to oleander and almond but not to grapevine) has been isolated in California (US).
Surveys are being carried out in Puglia to delimit the extent of the infected area. It is prohibited to move propagation material of any susceptible host species from the infected area. For the control of the disease, which does not seem to be exclusively due to X. fastidiosa, the adoption of further phytosanitary measures is currently being evaluated. In Italy, it has been shown that the subspecies that is occurring on olive trees is X. fastidisoa subspecies pauca.
To follow the situation in Puglia (IT): Emergenza Xylella

Symptoms on olive
Symptoms on olive
Symptoms on olive
   
Symptoms on olive
Symptoms on olive
Symptoms on olive

All pictures of symptoms on olive trees were kindly provided by Donato Boscia, Istituto di Virologia Vegetale del CNR, UOS, Bari (IT)
Franco Nigro, Dipartimento di Scienze del Suolo, della Pianta e degli Alimenti, Università degli Studi di Bari (IT)
Antonio Guario, Plant Protection Service, Regione Puglia (IT)

View more pictures >>

 

Situation in France: In July 2015, the presence of the bacterium was reported for the first time by France. X. fastidiosa was detected on a few ornamental plants (Polygala myrtifolia) planted in a commercial area in Propriano (Corse). Other foci were then detected on the island (both in Corse-du-Sud and Haute-Corse departments), mainly on P. myrtifolia (but other plants were also found to be infected). On the 13th of October 2015, the bacterium was discovered for the first time on the mainland. It was detected in the municipality of Nice (Alpes-Maritimes department - Provence-Alpes-Côtes-d'Azur region) in one plant of P. myrtifolia. In France, the subspecies which is occurring on P. myrtifolia plants is X. fastidiosa subsp. multiplex (thus differing from Italy, where it is X. fastidiosa subsp. pauca that is occurring on olive trees). At the end of October 2015, more infected P. myrtifolia plants (5) were found in Nice, and another focus was detected in the municipality of Mandelieu la Napoule (1 infected P. myrtifolia plant). At the end of 2015, several foci were found in Alpes-Maritimes and Var departments. In all cases, eradication measures have immediately been implemented in accordance with a contingency plan.
To follow the situation in Corse (FR): FREDON-Corse: Special Xylella fastidiosa - suivi des actions
To follow the situation in Provence-Alpes-Côte d'Azur region: DRAAF - foyers de Xylella fastidiosa en région PACA

 

The pathogen: X. fastidiosa is a xylem-limited fastidious bacterium. From a taxonomic point of view, it is a complex species and several research studies have suggested that the different strains which are found on different host plants might be grouped into subspecies (e.g. X. fastidiosa subsp. fastidiosa, X. fastidiosa subsp. multiplex, X. fastidiosa subsp. pauca, X. fastidiosa subsp. sandyi), however this concept is apparently still being debated among specialists. X. fastidiosa causes several diseases of economic importance: grapevine Pierce's disease; citrus variegated chlorosis; peach phony disease; plum leaf scald; as well as leaf scorch diseases on oleander, almond, coffee, pecan, and amenity tree species.


Insect vectors: In the Americas, numerous species of Cicadellidae and Cercopidae (Insecta: Hemiptera) are known to be vectors of X. fastidiosa. In Californian vineyards, Homalodisca vitripennis (=H. coagulata), Carneocephala fulgida, Draeculacephala minerva, and Graphocephala atropunctata are considered to be the most important vectors of Pierce's disease. In Brazilian citrus orchards, Acrogonia terminalis, Dilobopterus costalimai, Oncometopia fascialis are considered to be the most important vectors of citrus variegated chlorosis. It is thought that virtually all sucking insects that feed predominantly on xylem fluid are potential vectors of the bacterium. In Italy, recent experiments have shown that Philaenus spumarius (Hemiptera: Aphrophoridae) can transmit the disease from olive tree to olive tree. However, the existence of other possible vectors needs to be further studied in the EPPO region.

Carneocephala fulgida
Draeculacephala minerva
Graphocephala atropunctata
Some vectors of grapevine Pierce's disease.
Xyphon fulgida.
J. Clark - University of California,
Berkeley (US)
Draeculacephala minerva.
J. Clark - University of California,
Berkeley (US)
Graphocephala atropunctata.
A.H. Purcell University of California,
Berkeley (US)

 

Main symptoms: Symptoms vary according to the host plants but in general, as the bacterium invades xylem vessels and blocks the transport of water and soluble mineral nutrients, affected plants show drying, scorching, wilting of the foliage, eventually followed by plant death.

Pierce's disease
Pierce's disease
Pierce's disease

Pierce's disease of grapevine.
Symptoms in cultivar Chardonnay.
J. Clark - University of California,

Berkeley (US)

Pierce's disease of grapevine.
Symptoms in cv. Chardonnay (under

moisture stress). A.H. Purcell
University of California, Berkeley (US)

Pierce's disease of grapevine.
Persistent petioles. 
J. Clark & A.H. Purcell, University of California, Berkeley (US)

Peach phony disease
Oleander leaf scorch
Citrus variegated chlorosis
Peach phony disease.
M. Scortichini, Istituto Sperimentale
per la Frutticoltura, Rome (IT)
Oleander leaf scorch.

Wikimedia commons
Citrus variegated chlorosis.
M. Scortichini, Istituto Sperimentale
per la Frutticoltura, Rome (IT)

 

 

Host plants: X. fastidiosa is reported to infect more than 350 different host plants. The main economic hosts are grapevine (Vitis vinifera, V. labrusca, V. riparia), citrus (Citrus spp., Fortunella), almond (Prunus dulcis), peach (P. persica), coffee (Coffea spp.), and oleander (Nerium oleander).
It has also been reported on other fruit crops: e.g. Asian pear (Pyrus pyrifolia), avocado (Persea americana), blueberries (Vaccinium corymbosum, Vaccinium virgatum), Japanese plum (Prunus salicina), pecan (Carya illinoinensis), plum (Prunus domestica), sour cherry (Prunus cerasifera), as well as on many amenity trees: e.g. American sycamore (Platanus occidentalis), American white elm (Ulmus americana), liquidambar (Liquidambar styraciflua), oaks (Quercus spp.), red maple (Acer rubrum), red mulberry (Morus rubra).
X. fastidiosa has also been detected in lucerne (Medicago sativa). Numerous wild plants and weeds can carry the bacterium without symptoms (e.g. wild grasses, sedges, lilies, various bushes and trees).
Surprisingly, olive (Olea europaea) has rarely been mentioned as a host plant in the literature. However, studies were recently initiated in Southern California because increasing olive tree mortality was reported from the Los Angeles area. X. fastidiosa was consistently detected in olive trees showing branch dieback and leaf scorching but its pathogenicity could not be fully demonstrated (Krugner et al., 2010).

EFSA is maintaining a database on host plants of X. fastidiosa.

 

Geographical distribution: The distribution below is given for all host plants. For many years, X. fastidiosa remained confined to the Americas. In 1994, it was first noticed in Asia, in Taiwan causing leaf scorch on Asian pear (Pyrus pyrifolia). In the 2000s, it was also reported causing Pierce's disease in Taiwanese vineyards. In the EPPO region, the finding in Puglia (Southern Italy) represented the first confirmed detection in Europe. The introduction pathways of X. fastidiosa into Asia or Europe are unknown. However, it can be noted that EPPO member countries have intercepted several times X. fastidiosa on imported coffee plants from South America.
EPPO region: France (first detected in Corsica, and then also in Alpes-Maritimes and Var, under eradication), Italy (introduced in Puglia, under eradication).
Asia: Iran, Taiwan (introduced, first found in Asian pears and then in grapevine).
North America: Canada (Ontario), Mexico, USA (Alabama, Arizona, Arkansas, California, Delaware, District of Columbia, Florida, Georgia, Indiana, Kentucky, Louisiana, Maryland, Mississippi, Missouri, Montana, Nebraska, New Jersey, New Mexico, New York, North Carolina, Oklahoma, Oregon, Pennsylvania, South Carolina, Tennessee, Texas, Virginia, Washington, West Virginia).
South America: Argentina, Brazil (Bahia, Espirito Santo, Goias, Minas Gerais, Parana, Rio de Janeiro, Rio Grande do Sul, Santa Catarina, Sao Paulo, Sergipe), Costa Rica, Paraguay, Venezuela.

distribution map

 

 

 

EPPO information material

 

Other useful sources

 

 

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